Transformer and inductance



Nov 13,1928. 1 L69L699 A. D. CARDWELL TRANSFORMER AND INDUCTANCE Filed May 16, 1925 s Shets-Sheet 1 INVENTOR fl [Zen 0. (a/"dwell Q Q; [3M

ATTORNEY Nov. 13, 1928. 1,691,699

A. D. CARDWELL I TRANSFORMER AND INDUCTANCE Filed May 16, 1925 s Sheets-Sheet 2 INVENTO Allen 5. Cardw ATTORNEY Nov. 13, 1928.

A. D. CARDWELL TRANSFORMER AND INDUCTANCE Filed May 16, 1925 5 Sheets-Sheet 3 mm w o 0 an. M

40 I a v so that the lead. W1'I6Sf01' the-primary: will Patented Nov. '13, 1928.-

j STATES; P'ATENT" o-Fe ce;

. ALLEN. An w L a we m ai mma New max TRANSFORMER am)- mDUcrANoE.

' Application an may 15, 1925. Serial m. 30,666.

My invention. relates toimproveinents in coils ofwirefor eleotrlcalpurposes, such as in lnductances, transformers, etc., and embodies advantageous features. in coils in toroidal.

formi c: I I I One ofthe objects of myinvention is to provide a coil or electrical. element having cone ductorwindings wound in such a way that the electrical: cu1'rent will pass through the coilin parallel on its opposite sides or halves;

whereby the magnetic fields generated will be in conjunction, and the adjacent ends ofthe'windingswill beof the same electrostatic potential.

To carry out my invention. one side or half of the coilmay be Wound asto the right orv in a clockwise direction, and the other side or. half of the coil may be wound asto thelett or in counter-clockwise direction, with the corresponding ends of the windings; adjacent 1 or in close proximity andthe endsof the conductors at adj acent ends. of the coils joined electrically. The ends ofthe halveso f the coil may, be placed in relatively close proximity orjuxtaposition' without injurious e'fi'ectsbecausethe ends whichare close or abuttingare The individual layers ofwire as they progress in diflerentdiree tiousaround" the halyes or separate el'ements of the same potential.

of the coil are of the same potential on one side as the wires that occupy the same sym i'netricalposition. on the opposite side of the coil. 'lh'e greatest difference. of potential represented by the points of entrance and exit olT' -thecurrent which isat substantially on my improved coil used as the secondary,

not introduce any serious electrostatic capacity in the secondary.

Another object, is'to connect the turns of a claims.

g p distrib uted capacity .of'the coil. I

Reference is to be had to the accompanydifferent relation of the inner turns to the outer turns of a group;

Fig. 4 is a diagrammatic View of the'toroidal coil of Fig. 1;

Fig. 5 is an edge view. of an outer side of the coil; i i

Fig. (i'is a detail: perspective, on an exaggerated scale, illustrating the mannerct; tying the turns ofthe coil; I F'g. 7is aside view of a'toroidal coil have ingturns or windings in a single direction and substantially in'triangular cross section. spaced andretained in. accordance with my lnvention; v M

Fig. 8 is a cross section of Fig. 7

Fig. 9is a detail-side View ofaportion of the coil 'ofFig. 7' substantially rectangular in cross section; i

Fig. 10 is across section of'FigzQ;

- Figlil is a diagrammatic View of the coil ingits turns o rwindings spacedby binding mcans,.part of'whi-ch is without the coil and part within the coil;

- 17 is anendyi'ew of Fig. 16; p h

Fig. '18 s a detail perspective iew illustrating a core or tube Within the coil of -F1gn1-2;

Fig. 19 is a detail perspective View illustrating tube withoutthe coil of'Fig. 14; and

Fig; 20 illustrates thecoil of Fig. 16 within an outer tube.

bnnilar numerals of; reference indicate, corresponding parts. in the several views.

' The coil, which preferablycomprises in- ].sulated' conductor 1 maybe formed by Winding'the conductor with a suitable number of turns to form the desired completed toroid or coil, the outer or peripheral portions of the turns being laid side by side to so remain. In the form shown in Figs. 1 to 4 the coil comprises two windings 1, 1 of the conductor wire 1 wound in opposite directions, the turns of the windings 1 being shown in Figs. 1 and l as wound to the right hand or in a clockwise direction and the turns of the windings 1 as wound to the left hand or in counter-clockwise direction with corresponding ends of the two windings opposing. The right and lefthand windings may be made of the desired cross sectional shapeand conliguration, the corresponding ends of the two windings being'brought together so as to oppose or abut and they are so retained by suitable means. The end portions 1 1 of the two reverse windings'at one side of the coil are electrically connected, as by twisting the wires together, (Fig. l) and the end portions 1, 1 of said windings,on the side of the coil opposite the parts 1, 1", are electrically con nected, as by twisting the wires together. In accordance with the construction described when the coil is included in an electrical circuit the current will pass in parallel through both coils, and will create magnetic fields which will be in the same direction inasmuch as the current progresses through one half of the coil in a clockwise direction and through the other half in a counter-clockwise direction. Hence, the electro-magnetic flux will be in conjunction and the electrostatic fields will be separated by the total dimension of the coil, as determined by the distance between the first and last turns of the respective halves. The construction enables the ends of the two halves of the windings to be put in close proximity without injurious etii'ects because the abutting ends are of the same potential. The individual layers or turns of wire on one side as they progress around the toroid or coil are of the same potential as the turns of wire which occupy the same relative or symmetrical position on the opposite side of the toroid or coil. The greatest difference of potential is represented by the points of entrance and exit of the current to and from the coil which is at diametrically opposite sides of the latter. The coil described may be used as an inductance or an impedance, and

roidal coil. he primary winding may be in one direction only, or it may be of the splitparallel form described regarding coil 1, such as diagrammatically shown in Fig. 4, having the same magnetic and electrostatic characteristics. turns or windings may be of any desired shape, such as rectangular, triangular, hexagonal, or the like, in either of the forms illustrated.

In order to provide the toroidal coil with a relatively large number of turns within a relatively small compass the diametrically inner parts of a. given number of adjacent turns, say three of such turns, are located one within another in groups or series with the corresponding outer turns side by side.

As illust ated in Figs. 3, 3 and 6 the inner turns 2, 3, t of a group ol turns lie or are nested within one another, such that the inner parts of every third turn will lie at the inner circumference of the toroid, (each part 2 counting as number one in a group or series of three), with the corresponding inner portions 3, 4; of each group or series of three coinplemental turns nested or lying within the part 2 of the same group and within one another, with an air space between said turns, all within the area bounded by the first turn on the outer periphery of a given group, the

last turn on the same periphery of the same group and the particular turn of the group at the inner circle of such group. Said area is shown within dotted lines in Figs. 3 and 3". In Fig. 3 the inner turns at 2, 3, 4 are substantially in a radius of the toroid, and in Fig. 3 the turns incline from a radius. The construction is such that with the groups of turns arranged as described no turns of one group will rest on or lie within any turns of an adjacent group of turns. lVhile the turns or convolutions of the conductor corresponding to the parts 3, 4 are concealed at the inner portion 01' the toroidal coil by the companion outer parts 2 the continuations thereof appear at the peripheral portion of the coil in full and appear more or less graduated from the inner circle to the outer periphery of the. coil, on the radial-like lays. The turns may be formed in substantially rectangular form, as illustrated in Figs. 2 andlO, or in a substantially triangular form, as in Figs. 6 and 8, or the coil may be wound in other desired form.

In accordance with the construction described I am enabled to provide a coil having a relatively large number of turns or convolutions located at the peripheral portion in a single layer side by side, andthe inner por tions nested as may be required to preserve the substantially radial lines of the turns. and within a relatively small compass. \Vhile 1 havereferred to the coil as comprising a series of three complemental turns 2. 3. 4:. adapted to nest at the inner portions, which I find in practice to be a satisfactory and practical form The cross sectional area of the Inn icense of toroid, it will be understoodthat two, three ori'nore of such complemental nested of turns, the several sets. are placedin juxta position but not Within one another by locating the inner turns 2 side by side. By the means described. the distributed capacity of is reduced to-a mini v i site, so that any external field will beneutralized, to minimize the effect of stray signals on they completed toroid mum. I

The turns of the element or coil may be retained in any desired way, such as by means of suitable binding connections; The turns.-

maybe tied togethenor a cordor cords may be within or without the 0011', serving toretain the turnsor convolutions. of the coilin normal or defin te relation and serving a supporting means The binding connections may bein the form of a non-conductingcord or strip. [The binding may beindependently attached to. oil-ch of thetum's. or convolutions.

at the outer or peripheral portion of the coil and abin der may be attached to eachseries or group, (2, 3 4) of turns or convolutions at the inner circleof the coil. At 6 the bind-. ing cord runs. completely around Within. the outer portion of the coil and at 7 is another cordlooped across each of the turnsor convolutions at the outer. part ofthe coil and aroundthe binding cord 6, forming a bind or tie at eachturn, whereby each looped portion of the binding is interposed between two turns. at the outer periphery of the coihthereby securingtheturns together and spacingthe turns apart. At the; inner portion of the toroidal, coil binding cords. 8 pass around.

As illustrated one cord is within the inner turns 4, and other cords between the turns 3, 4,

and 2, 3, for spacing them apart andabinding col-d9 islooped acrosseach three turns or convolutions of wire and encloses three bind; ing cords 8, preferably in a single.loop, t'or each group or seriesof turns,whereby the wires of each grouper series of .turns are spaced from each other acids 8 and each group or series of turns atthe inner part of the coilis spaced from the adj acentjg'roups by i the cord 9. The cords 6 and S'Q fiQITdRDOhQIr.

ages for the severalloops of'the binding cords 7 and 9. The fasteningof the binding tothe turnsof the coil retains: the turnsin spaced relation, andtl 1e inner ends of the binding cords at the adj acent ends of the coil may be. tied tge'ther at'll, toretain the coil: in toroi-v dal 'forlnforuseQ The spaces-between the adj acent turns and. setsor groups of turns will reduce the distributedcapacityofthe coil,

and thereby increase itseficiency either as an;

' inductance or as'a transformer. n One or more of the cords S'may be ,omittechin which case preferably the inner cord v8 will be used, The

same construction. of tying. and spacing the turns togethermay apply either tothesecondary winding or to the primary Winding 5,01: toboth, 7

A. toroidal transformer or inductance con structed in the manner'sct forth will have numerous advantages. The fields are concentrated in. a confined area: and are entirely closed so that losses due to stray fields are reduced, stray signals passing through the coil will; generate a current on one sideequal and opposite to any current whichmay be gen; 7

eratcd in the windings diametrically oppothe toroid. Conversely, any magnetic fiel generated by the turns on one side of the to,- roid, Will have an oppositefield generatedby the turns on the opposite side of the toroid, so that magnetic feed-back or undesirable magnetic couplingwith any; other circuit will be reduced. This will permit the concentration of comparatively large inductances in a small area without the disadvantage of having intense external magnetic fields, and also permit the use of comparatively large-air core transformers or inductances without generatturns or windings are spaced apart and retained improved binding, however, is not limited to the toroidal form of COll since the binding may be used with other shaped coils or windings as elements'or parts of electrical instruments. In Figs. 12 to 20 I have illustrated my improved binding utilized in connection with coils in straight form with cords or the like 6 passing along the coil or conductor 1 and the binding cords 7 looped l on across the turns of the conductor and around [the corresponding longitudinally disposed cords 6, securing the turns or windings of the coiltogetherandspacingthein apart. In Figs.

:12 and 13the cords 6 extend longitudinally Within theturns of the coil; in Figs. 14 and 15 cords v6 extend longitudinally along the outer surface Ofitl-IG coil, and in Figs. 16. and 17 some cords 6 are within and some cords G are without thecoil, allot such cords being tied to the turns of the coil by the binding cords 7 which space the turns apart, and overlie or underlie the conductor, 1. At the ends of the coils the respective complemental cords 6, 7- may be tied t-ogethensuch as indicated The coilsofFigs. 12 to 17 will be sufficiently firm to be used Without acore therein 01' a cover thereon for various purposes. Said coils, however, may be used with an inner core or tube of suitable material, preferably of insulation, indicated at 12, the coil being spaced from the core or tube by the-binding cord7that projects from conductor 1 either exteriorly or interiorly of the coil. In Fig. 18 the form of coil shown in Figs. 12 and 13 has a core or tube 12 therein and the longitudinal cords 6 and the underlying binding or looping cords 7 that project within the circumference of the windings beyond the conductor and cord 6 of the coil serve to space the coil from the tube or core. In Fig. 19 the coil is inserted with in tube 12 and in this case the cxteriorly disposed cords (S and the overlying bindings 7 projecting beyond the conductor and cord 6 serve to space the coil from the inner surface of the tube. In Fig. 20 the tube 12 encircles the coil 01 Fig. l land is spaced therefrom by the exterior cords 6 and the looping cords 7, other cords 6 being within th coil. In the form of coil of Figs. 16, 1'7 and 20 a tube simi lar to 12 may be within the coil in the man ner shown in Fig. 18, and a tube may or may not be around the coil.

Although in Figs. 1 to 10 I have hereinbetore referred to the conductor 1 as being an insulated conductor it will be understood that in all cases the conductor need not have an insulating covering, as where the bllltllngpl looping cords or elements 7 or 9 pass between adjacent turns or" the coil, and also where the spacing cords or elements 8 are located between nested turns of the coil, since such parts 7, 8 and 9 serve to separate the conductor turns in spaced relation, thereby insulating them from one another. The looping cords also serve to insulate the non-insulated conductor from tube or core 12.

I use the term cord in the specification and claims in a generic sense intending it to mean ordinary cord or twine in round or other cross section, or a strip of tape or ribbon-like element of insulating material, which may be used extending along the wind ings of the coil and as looping or binding the turns or windings of the coil as well as spacing them apart.

While I have illustrated and described the element or coil as provided with several cords extending along the same, it will be understood that such elements or coils may have one or more of such cords with the binding or bindings looped around the turns of the coil and the cord or cords, or around the turns of the coil only for spacing and binding the turns with the cords (5 orS, or both, omitted. The element or coil may be made without the cords and binding, (Figs. 3*, 3 and may be retained in toroidal form in any desired way.

\Vhile the elements 6 and 8 have been referred to as cords, they are employed to form ribs to which the windings are secured or lashed by the binding cords. These elements 6 and 8 may, of course, be of ditlerent sizes or diameters and they may consist of textile material or they may be in the nature of dielectrics, such as rattan, rubber, or bakelite rods or strips. In using the ribs and binding cords, the cross sectional dimensions of the combined ribs and binding cords may be determined in order that when the coil is ap plied to a'supporteither internally or externally of the coil, the coil will be held in effective spaced relation to the support. Furthermore, by the employment of the rib and binding cord, the distance between the turns of the coil may be determined by the cross sec tional area of the binding cord and, of course, the distance between the turns will be changed according to the diameter of the binding cord;

Having now described my invention what I claim is 1. A toroidal coil comprising a conductor having turns whose peripheral portions are located side by side and inner portions of groups of turns adjacent, means securing the outer turns together and spaced apart, and means securing said groups of turns together and spaced apart from other groups.

1 2. A toroidal coil comprising a conductor having turns whose peripheral portions are located side by side and, inner portions of groups of turns adjacent, and means securingturns of each group together radially and spaced apart with the groups spaced apart. 7

3. A coil for electrical purposes compris' ing a conductor having turns, a rib extending at approximately right angles to the turns, and means between the several turns encirclingthe conductor and rib for securing the conductor to the rib.

4. A coil for electrical purposes eompris= ing a conductor having turns, a rib extending axially of the turns otthe coil, and a binder embracing a turn of the coil and rib for securingthe turn to the rib and holding the turn of the coil in spaced relation to other turns of the coil.

5. An electrical element comprising a conductorhaving turns, a rib extending at approximately right angles to the turns, and bindings looped across the turns and around said rib, holding the turns in spaced relation to one'a'nother.

, 6. A coil comprising a conductor having turns whose peripheral portions are located side by side c'ircumt'erentially and whose turns are arranged in groups at the inner portions, a rib extending through the turns at the peripheralportion oi the coil, means extending between the turns for securing the coil to the rib and spacing the turns apart, the turns of each group being spaced from each, other, ribs extending between the turns, respective means for securing the turns of each group to a respective rib and in radial so V too

alinement and for holding thegroups in alined, and means for securing the said alined turns in spaced relation to each other and in spaced relation to turns of the other groups of the coil.

8. A coil for electrical purposes compris ing a conductor having turns, a rib extend ing axially of the turns of the coil, a binder embracing a turn of the coil and a rib for securing the turn to the rib and holding the turn of the coil in spaced relation to other turns of the coil, the cross sectional dimension of the rib and applied binder determining the distance that the coil Will be held from a support to Which the coil may be aplied. a p 9. A coil comprising a conductor and turns adjacent, a rib extending axially across the turns, and a binder looped across said turns and around said rib and spacing said turns apart.

10. An electrical element comprising a conductor havlng turns, ribs extending across the turns in spaced relation to each other, and

binders looped around the turns and around said ribs spacing the turns apart,

r ALLEN D. CARDVVELL. 

